Adjuvant administration of radiation therapy with hyperthermia in treatment of cancer has been studied extensively in the past three decades (Deger et al., 2004), but simultaneous delivery of these modalities using the same source has not been documented. Here we propose feasibility study, development and clinical implementation of a new Thermo-brachytherapy seed that combines a sealed radioactive source with a ferromagnetic core serving as a self-regulating hyperthermia source when placed in an alternating electromagnetic field. The proposed new seed is based on the conventional 125I seed commonly used for prostate implant with addition of a ferromagnetic core in place of the tungsten marker to be implemented as a heat source. In addition to being used as a source for both radiation and heat at the onset of cancer therapy, these implanted seeds could be used for thermal re-treatment of the tumor in case of recurrence, possibly as a sensitizer to systemic therapies without another invasive procedure. The combination of a magnetic field and a self-regulating seed will preclude the need for invasive thermometry and provides relative ease of the heat delivery especially to deep-seated tumors. With this approach heat self-regulation is achieved by employing the Curie temperature of a ferromagnetic metallic alloy, distinct to its composition, leading to drastic decrease in heat production after reaching the targeted treatment temperature range. This innovation is in contrast to clinically available technology where hyperthermia is delivered by microwave and ultrasound applicators resulting in limited penetration and the inherent need for invasive thermometry. The goals for this project include: complete dosimetric characterization and evaluation of this newly developed dual function seed using Monte Carlo simulation, and characterization and evaluation of its thermal properties using the finite element modeling. Through our partnership with the University of Toledo we aim at development and manufacturing of a prototype, and studying its efficacy in concurrent delivery of radiation and heat. The interdisciplinary team of experts assembled for this project covers all anticipated aspects of the proposed project, including scientific, engineering, and clinical issues, thus ensuring the successful achievement of the specific aims set forth. Successful completion of the Phase I will propel the project into the Phase II stage of development of a fully functional seed prototype. Successive translation of the prototype into a highly effective clinical procedure of concurrent administration of brachytherapy and hyperthermia for prostate cancer treatments will prepare Thermo- brachytherapy seed for immediate commercialization. PUBLIC HEALTH RELEVANCE: Of the nearly 187000 men estimated to get the news for prostate cancer this year in US alone, about 1 in 6 will die from it based on statistics published by the American Cancer Society. The technique proposed in this project has the potential to reduce this ratio and increase the probability of tumor control without a significant change in treatment regimen currently offered. Through an innovative technology and modification of an existing radioactive implant, an adjuvant fractionated hyperthermia treatment can be integrated into radiation delivery procedure, and can be used for salvage therapy in case of a failure by re-heating the gland via the already implanted seeds.